Telephone-receiver



(No Model.)

J. A. GHRISTY & JLBALDWIN.

TELEPHONE RECEIVER. No. 471,535.

Patented Mar. 29, 1892,

after/14213 Nrrso STATES PATENT OFFICE.

Y JAMES A. CHRISTY AND ELIAS J. BALDWIN, OF SAN FRANCISCO, CALIFORNIA,

' ear-piece.

TELEPHONE-RECEIVER.

SPECIFICATION forming part of Letters Patent No. 471,535, dated March29, 1892.

Application filed March 16 1891.

To all whom it may concern:

Be it known that we, JAMES A. CHRISTY and ELIAS J. BALDWIN, citizens ofthe United States, residing at San Francisco, in the county of SanFrancisco and State of California, have invented certain new and usefulImprovements in Telephone-Receivers; and we do declare the following tobe a full, clear, and exact description of the invention, such as willenable others skilled in'the art to which it appertains to make and usethe same, reference being had to the accompanying drawings, and to theletters of reference marked thereon, which form a part of thisspecification.

Our invention relates to improvements in telephone-receivers, and hasfor its object the provision of certain novel features of construction,as will be hereinafter described, and pointed out in the claims.

, \Ve provide a cup-shaped base having a fiat cover, under whichcoverthe diaphragm is mounted, and to the said opening on the outside issecured the apex of a bell-shaped The base is secured to a hollow shank,preferably of semicircular form in length, in which a magnet is placed.In the chamber of the cup-shaped base are provided perforate tubes ofmagnetic material, which extend from the diaphragm to a centralperforated ring-tube surrounding the opening to the hollow shank. Thering-tubeis also made of magnetic material, and over it may be placed aperforated dome. These tubes are connected to the magnet at the openingto the hollow shank and serve to convey the magnetic action onto thediaphragm. The perforations in them also serve a useful function in thesound-chamber.

The body of the receiver is made of nonmagnetic material, preferably ofa combination of papier-mach, ore-.paple, hard and soft rubber, cork,wood pulp, cinder, and brass, copper, or aluminum.

The following detail description more fully explains the constructionand purpose of our said invention.

In the accompanying drawings, Figure 1 is an elevation of the exteriorof the base and ear-piece with a portion of the shank attached.

Serial No. 385,315 (No model.)

Fig. 2 is a sectional view of the entire instrument. Fig. 3 is a planview of the cup-shaped base with the perforated tubes, the cover,diaphragm, and dome of the tubes being removed.

Similar letters of reference indicate correspending parts in all thefigures Where they In the sound-chamber H are. provided the" perforatedtubes D and E, which are formed of magnetic material and are connectedto the magnet L in the hollow shank C and extend up to the diaphragm.These tubes are preferably made in the form of a central ring-tube D,which surrounds the opening be tween the sound-chamber and the hollowshank and over which the perforated dome F may be placed, and the three(or more or less) radial branches E E, which reach up to and formcontact-points on the under side of the diaphragm at its periphery,while the ring D has the end of the magnet L soldered to it. The polesof the current are'connected to binding-posts r q; but it will beobserved that we have magnetic connection with the diaphragm at three ormore points, as already stated, around its periphery instead of at onepoint, as is now customary in telephone-receivers.

Having thus described our invention, what we claim, and desire to secureby Letters Patent, is

1. In atelephone-receiver, the combination, with the diaphragm andchamberin which it is mounted, of a system of perforated magnetic tubesin said chamber connected to the actuating electro-magnet and extendingup of a cup-shaped base having a flat cover, a

diaphragm mounted under said cover, and an ear-piece mounted on saidcover, with a per- In testimony whereof we affix our signatures foratedtubular magnetic ring-tube placed in in presence of two witnesses. thebottom of the cup-shaped base, perforated JAMES A. OHRISTY. magneticradial tubes extending from said ELIAS J. BALDWIN.

5 ring-tube to the diaphragm, and a magnet Witnesses:

connected to the said ring-tube,substantially M. A. FRENCH,

as set forth, Gno. W. BALDWIN.

